1. Field of the Invention
The present invention relates to an endoscope image pickup unit that is configured by an image pickup device, which has connecting terminal portions on a back surface, being mounted on a flexible printed wiring board.
2. Description of the Related Art
In order to observe spots that are difficult to observe such as interior portion of a living body, structural object, etc. for example, endoscope with image pickup units for picking up optical images is commonly used in medical and industrial field which is possible to introduce from the outside portion.
An endoscope image pickup unit is formed by including an objective lens that forms an image of an object, and an image pickup device that is placed on an image formation surface of the objective lens, and is generally called a CCD (charge-coupled device), a CMOS (complementary metal oxide-semiconductor) sensor or the like.
In order to make a mounting area on the substrate small, some image pickup devices have configurations such that connecting terminal portions for electric connection with a substrate are provided on a back surface that is opposite to a surface (a light receiving surface) on which light is incident. For example, Japanese Patent Application Laid-Open Publication No. 2007-73958 discloses a package of an image pickup device which is provided with connecting terminal portions on a back surface. If the image pickup device having the connecting terminal portions on the back surface like this is used, it is possible to make the mounting area small.
When the image pickup device having connecting terminal portions on the back surface, as disclosed in Japanese Patent Application Laid-Open Publication No. 2007-73958, is used in an endoscope image pickup unit, such a form can be adopted that the image pickup device is mounted on a flexible printed wiring board, the flexible printed wiring board is bent to be extended rearward (a direction opposite from an object) along an optical axis, and an electric cable placed in an endoscope is connected in a distal end portion of the flexible printed wiring board. As above, the flexible printed wiring board on which the image pickup device is mounted is bent and extended rearward, whereby a projected area of the outer shape of the image pickup unit onto a plane that is orthogonal to the optical axis can be made small.